Metal bending and stretching apparatus



J. S. NIELSEN ETAL METAL BENDING AND STRETCHING APPARATUS Nov. 26, 1946.

Filed Sept. 1i, 1943 3 Sheets-Sheet 1 .james 6. Nie/51221K -Nov. 26, 1946. J. s. NlELsEN ETAL 2,411,801

l METAL BENDING AND STRETCHING PPARATUS Filed Sept. 11, 1943 Sheets-Sheet 2 Patented Nov. 26, 1946 METAL BENDING AND STRETCHIG APPARATUS ,Y 'rames s. Nielsen, Stow, ana Clyde B. Machala,

Akron, Corporation,

Delaware 0hio, assgnors to Goodyear Aircraft Akron, Ohio, a corporation of Application september 11, 1943,*seria1na501p16 f This invention Yrelates to 'metal stretching and bending apparatus, and, vin particular, to an apparatus for forming straight bar material of metal and the like of any cross Sectional conguration into smooth contours of predetermined shape by stretching the stock material and at the same time Winding it around a forming die.

' Machines are known on which a tube or the like is bent without stretchingaround a die. How'- ever, in this case a male and a female die are required to avoid wrinkling of the material and the rather expensive die does not give satisfactory results without compensating the die for springback of the material.

Other'machines are known which apply stretching while bending oi the work piece takes place. However, machines of this type, although producing satisfactory'work ori-some sectionsand sizes, are bulky and heavy in construction, require a large spaceand considerable personnel, and are not adapted'f or bending through an angle of more than 180 degrees, but usually operate to through angles or" much less than '1189 degrees.

4The! present invention avoids theA shortcomings of these known constructions by a novel arrangement whereby the stock material is stretched and at the same time is Wound around a form block or die secured to a turntable. The stretching means, usually a hydraulic cylinder, is vattached to an endlesschain which passes'around a sprocket secured to the turntable at one end and an idler sprocket mounted at the opposite end of the Work table. y As the table rotates, the cylinder moves toward the turntable, at exactly the same lineal' speedas the periphery of the sprocket.'

' Twofpneuma-tically operated jaws are employed to hold` the stock, one jaw being fastened tothe piston rod of the'cylinder and one jaw being sep cured to the turntable adjacent theform block. The construction of the apparatus is such that a constant or controlled tensile force is exerted on the Ypart during the entire vforn'iing operation. Owingrto the fact that the distance fromform' block contour to the center of theturntable may vary, the circumferential speed of the form die usually differs' from the speedof the hydraulicA cylinder. This' diiierenc'e'is compensated for by the movement vof the'fpiston in" its cylinder, thus always securingthe necessary tension inthe' work piece. `4 The finishedflarticle thus formed on this machine has fa smooth surface vfree from wrinklesr` and conforms perfectly to the shape of the form' die with practically no spring back. Y

The main object ciA this inventionv isl the provision of apparatusfor formingr rolled, extruded 13 Claims. (Cl. 153-40) 2 or sheet metal bars around a revolvableform block without spring back.

Another` object of the invention is to provide apparatus for forming metal, or like material,

- around a form block over van angle of more than about 180 degrees.

Another object of the invention'is the provision of compact apparatus of the type described and which is relatively inexpensive to build and to maintain, long wearing and easily operated in use with a minimum of readilytrained personnel, and

which rapidly and efficiently turns out high grade and uniform work.

Another object of the invention is to provide apparatus of the character described and operable solely with a iluid pressure motor.

Another object of the invention is the provision of a modification of the apparatus wherein the sprocket and chain assembly need not be employed.

Another object of the invention is the provision of a sectional or multi-part die for forming metal substantially without spring back.

Other objects of the invention will appear as 5 the description proceeds.

For a better understanding of the Y invention reference should be had to the accompanying drawings wherein: f Figure 1 is a topplan View of o-ne embodiment of the invention showing a work piece in the machine after a, completed bending operation;

Figure 2 is a front elevation of the apparatus of Y Figure 1 with the front supports broken away for a better showing of the driving mechanism ofthe 'i machine;

Figure 3 is a fractional section through the table on line IIT-IIIfof Figure 2;

K Figure 4 is a diagrammatic plan view'illustrat-l ing the manner in whichthe apparatus of Figures 1 to 3 can ber operated without a motor.

Figure 5 isla diagrammatic` plan View of a mf'idi--.y

neat-ion of the apparatus of Figures 1 to'3;

Figure/6` is a plan lView 0f a multi-part forming die; Y

Figure 7 is a'sectional view taken onerline VI- VI of Figure 6; f

Figure 8 is a sectional view taken on line VIEI- VIII of Figure 6.

The apparatus of the invention in oneL best known embodiment consists of a table, indicated as a whole bythe numeral l, and including supports l2 to which is secured a top I4 at the ends of 4which are mounted vertical shafts IB and I8 in bearings 20, 22 and 24,- 26, respectively. The bearings 2li and 24 are fastened to the table top and the bearings 24 and 26 to transverse channels 23 connecting the table supports. To each one of the shafts It and I3 just beneath the top of the table is keyed a sprocket 3@ which sprockets are connected by an endless chain 32. The shaft |8, which extends through and above the top of the table, carries at its upper end aturntable or die support 34 provided with anchor Vslots 36. The shaft IS is preferably driven, usually by an electric reversible motor 38 of the variable or multispeed type, and operates a reduction gear box 48 located underneath the table.

In the chain 32 is inserted a special adjustable link 5E] to which is attached, by bolts 52, a slide or cross head 54 consisting of bottom and top parts 5t and :18 connected by bolts 60 and slidable in a slot B2 in the table top I4. In the upper part 58 of the slide is a, fixed pivot stud 62 about which is rotatable a support 66. To prevent eX- cessive tipping stress on the stud 62 the support 66 is held against the upper slide part 58 by one or more gib fingers 68.

To the support G5 is bolted in a vertically adjustable manner a hydraulic power cylinder which furnishes the power for stretching the work material W. The cylinder lo includes a piston 'r2 having a hollow piston rod 'i4 which carries at one end a gripping device it having movable jaws 86. The side of the piston opposite the rod 'F4 is provided with a hollow rod extension S to the end of which is attached a bracket 80 supporting a small pneumatic cylinder 82 having a piston rod 534 which extends slidably through the hollow bore of the extension 28 and rod 14 to operate the jaws 86 in the gripping device 1B.

Another gripping device 88 is adjustably mounted o-n the turntable 34 by clamps Sii. This device also is provided with a small pneumatic cylinder 92 operating jaws 86a by which the end of the work piece W is held while being stretched and bent over a form die It@ mounted on the table.

It will be understood that the work W is` stretched between the gripping devices V'i6 and 83 as it is bent around. the form die IDG which is adjustably mounted on the turntable 34. More particularly, the die it) may take a wide variety of shapes, sizes or constructions, but in the form illustrated it is made of two pieces |32 and |04 bolted together and which in assembled complementary relation form a curved groove into which a portion of the work piece W slidably fits. IThe forming die mi) is either xedly or swingably mounted by two bolts |85 and |68 to a block ||il which in turn is fastened to the turntable 34 by clamps QG. The forming die when it is made swingable about the bolt it is (as is usually the case when material is to be bent through an arc approaching 180 degrees) provided with an arcuate slot l2 of suitable length through which passes the bolt |86 thereby forming a stop tothe -arcuate movement of the die in either direction.

Provision is also made for fixing the relative position of the die and its supporting block by placing the hole ||\B in the die over the hole ||8 in the block and by inserting a locking pin therein.

For supplying the hydraulic cylinders with fluid under pressure and to make the apparatus independent of available uid pressure lines, a

pump |26 is ordinarily provided which is driven by an electric motor |22 and with the pump being fed from a service tank |24 to which the uid, usually oil,vreturns.

The operation ofthe machine is very simple the machine ready for operation the turntable 34 is rotated to position the gripping devices I6 and 28 in alignment and a distance apart about equal to the length of the work piece. The work piece then is inserted in one pair of jaws and then in the other pair of jaws by moving the piston 'I2 back or forth, as the case may be, by supplying controlled amounts of uid thereto from the pump iv2il. With the forming die and its supporting block rvlocked against relative movement, the turntable is put in motion by operation of the motor 38 and the work piece W is brought under suicient tension by the controlled flow of fluid to the cylinder 10 to permanently stretch the material the desired amount. The stretching of the work piece prevents wrinkling of the material during the bending process. The pivotal mounting of the power cylinder support results in the stretching force being applied to the work piece in a direction which is always tangent to the circumference of the forming die. The tension on the work piece, and, accordingly, the permanent stretch thereof may be regulated during the bending operation to obtain the best results and a perfectly smooth article Without any spring back. In many cases,l however, the tensio-n or stretch applied can be kept constant during the bending process.

In cases where the bending angle on the work piece is obtuse or not smaller than degrees and the bending radius not too small the die can remain fixed to its support without resulting in spring back. However, in c'ases where the turntable is rotated through more than a right angle to bend the work piece to less than a right angle, and particularly when the work piece is bent around a small radius, itis very advantageous to make the die swingable while or after the bending is performed. One manner of achieving the swinging of the die is to position it so that the slot ||2 is on the side of the bolt opposite from that shown in Figure 1. The die is then fastened on the block suiciently tight to permit some slippage so that when the turntable rotates the friction between the work piece and the die will tend to and will turn the die.

Another, and usually a preferred way of operating the pivoted part die, is to complete or substantially complete the bending of the work piece and the rotation of the turntable before removing the locking p in. Thereafter, the locking pin is removed and the work piece is given a nal stretch accompanied by a rocking of the pivoted part of the die. The important feature in this operation is that the nal and setting stretch thereby imparted to the work piece is not concentrated at one end of the Work piece (as is the casewhere the friction between the die and the work piece of a fixed die prevents the pull on one end of the work piece from being transmitted to the other end thereof), but is applied equally `toboth ends of the work piece by the rocking of the die. n

In vthe operation of the ,apparatus it will be` understood that as the work piece is bent around the die block the sprocket and chain drive moves the support for the hydraulic cylinder towards the die block whereby only aA relatively short hydraulic cylinderis required as distinguished from a long awkward cylinder which might otherwise have been necessary. Further, hydraulic control of the tension and piston movement in the cylinder is facilitated particularly where the die block is positioned on the turnon yeach vertical shaft and av hydraulic cylinder associated with each stretch of the chain 32 extending around the sprockets 35.'. rlhusa second setof rstretching and bending devices is provided opposite the'one shown, thereby doublingthe productive capacity of the machine without increasing its size.

From the description it will be recognized that the present invention is a decided` improvement over previous constructions oi stretch-bending machines in that its output is of the highest quality and perfection in smoothness as well asin shape and withspring back substantially eliminated. The articles made by the improved apparatus and by a minimum of ordinary personnel can be produced inexpensively, rapidly, and with little waste oi material. Besides, the space required for the improved apparatus is smaller and its cost lower than that of machines for similar purposes.

Turning now to Figure 4 of the drawings, there has been diagrammatically illustrated a modification of the improved apparatus wherein operation is achieved: without an electric motor 38 or other means for rotating the turntable; More particul'arly,A it is entirely possible and permissible to employ the hydraulic cylinder l@ of the apparatus toachieve both stretching and bending of the workpiece. This'result can be accomplished, in the inodication of the invention illustrated, inasmuchas the hydraulic cylinder iba vhas lits piston rod `connected to therv work pieceWa, as already described, with'the work piece extending around a. die block idea; The pulling force on the Work piece Wd is transmitted'through the cylinder'ldd to the chain 32a, as before described with respect to Figures 1 to 3, and thence to the sprocket 36a and the turntable 34a. Y Accordingly, the turning moment on the turntable 36a is equal kto the stretching` tension put into the work piece "multiplied vby the sprocket radius R2, minus the stretching tension multipliedeby the radiusk Rl from the centeror" the turntable-'to the tangent ofthe die "block,A minus themoment duev to irictional resistance.. Inotherv wordsi-as long as the radiusoithe" chain-'sprocket 3Go is somewhat greater than theradius oi 'the die block :leed mOunte-inhthe turntable, any forcerappliedjtofthe cylinder ldd to stretch the worklpiece We willY also result infarotation ofv the turntable toi-bend or wind the workpiece around the formblock mila.

. By applyingaisuitablecontrollablebrake, indicated as awholeby the'num'eral Zell, to the rotation ofthe turntable Silmthe desiredvrelation between #the bending and the stretchingy of the workpiece canbewcontrolled; The brake has been'conveniently' shown as applied tofthe shaft i3d mounting oneofvthe'sprocketsar v Y In Figure 5l is illustrated still another embodiment 'ci the invention 'wherein' theV sprocket and chain mechanism has been eliminated for movingthe hydraulic cylinder towards the die 'block during 'tl'ie-bendinT operation'. This modiiication ismost conveniently employed in conjunction witha particular die block, such as Vindicated at'lllilb,v

which when positioned as 'shown on turntable 342) can be turned by the turntable to wrap the rWork piece around it, all vwithout appreciably changing the position of the piston in a iiXed .hydraulic cylinder 'lh but which is'free to turnabout a vertical pivot.

In this embodiment of the invention thetnrntable- 34h 'must be rotated by positive turning and.

bending means, andthe entire kapparatus may tal-:e the form of a Vseparate machine having a somewhat longer hydraulic cylinder to take care VAendy lor the work piece.

i In fthe operation of:

of any discrepancies in the windup of the work piece. On the otherhand, lthe apparatus of -iigures 1 to 3 may be modied to have a stationary pivot post or hole to which the hydraulic cylinder can vbe moved for operations uponcertain work pieces and .dieblocks., a

Figures 6, 7 and S kshow a modiiication of the die blockoi the preceding igures of the draw-r ings. More specifically, in the embodiment of the invention of Figures l to 3 the entire die block is made movable, whereas Figures 4 and 5 show stationary die blocks. In Figures 5, *l 8 part of the die block isrigid and Vpart is movable.

It should be understood,=of course, that the various die blocks are interchangeable on the several forms of the invention shown, the use of any particular block being dependent upon theparticular shape to be formed of the-work piece, all as already explained heretoiore.-

In Figures 6 to 8, the numeral 2li) indicates generally a turntable to whichv is adjustably b-ut xedly secured b-y clamps 2id a pillow' 2li?. The pillow has a multipart die block 215, 2 i8 mounted thereon, the part 216 being rigidly fastened to the pillow and the part 218 being .,pivotally mounted as shown with'a stud bolt 22d. Each part of :the die block. in the form shown to producela curved channel is conveniently made up' of relatively thin plates mounted top and bottom of the main dieblock and with the thinv plates bein'ggrooved :to receive the side flanges of the channel workpiece being formed. The turntable 2li? is-rirovi'dedl with a clamp 22e to receive the 'the apparatus, and with the parts in lthefdotted'line position shown, the turntable is'rotated in a clockwise direction to move vthe die block to the 'solid line position shown.` During the associated bending and stretching operation the movable segment lla of the-die may be left free to move or it may be held against movement until near the end of the operation, all as already described in conjunction with the apparatus of Figures i to 3. In any event-"by employing one or the other 'of the stretching andbendi'ng operations, a widevariety of irregularlyor regularly changing radius forms'V l Having now described the invention in detail in reference to the drawings' showing but icertain examples ofi construction, it should clearly be not restricted' understoo'dfthat the invention is thereto blut many deviations tliereironfil may bev 'made within thescope andspirit of the appended .C1aimS.: f f, Y

lWhat is claimed is:'V y i. AA combines stretching and bending ma' Vcl'iinevffo-r,shaping elongatedmaterial int'ocon-l tours, oomprl l ng'a rotatable bending means having the "contour to lwhich thematerial is tofbeV bent, means movable with said bending means for gripping one end of said material, means for rotating said bending means, uid pressure actuated stretching means adapted to grip said material at a point spaced from said bending means for imparting a stretch to the material as it is bent around the bending means, means mounting the stretching means for movement to and from the bending means, and means controlled by the rotating bending means for controlling the to and from position of the stretching means.

2. A combined stretching and bending machine for shaping bar material into contours, comprising two shafts positioned in parallel relation a suitable distance apart, a sprocket on each shaft, a chain actively engaging said sprockets and having two longitudinal portions moving in opposite directions, die block means carried for rotation by one of said shafts, stretching means attached to said chain and being in cooperative relation to said die blo-ck means, and a reversible power unit in driving connection with one of said shafts.

3. A combined stretching and bending machine for shaping bar material into contours, comprising a shaft, endless iiexible means engaging said shaft and having two longitudinal portions moving in opposite directions upon rotation of the shaft, a form block mounted to rotate with said shaft, a pivoted support fastened to said flexible means, stretching means including a hydraulically operated cylinder adjustably mounted to said pivoted support and being cooperative with said form block, and a power unit in driving connection with said shaft.

4. A combined stretching and bending machine kfor shaping elongated material into contours,

comprising a table, a vertical shaft passing through and being journaled adjacent one end of said table, bending means xed to said shaft, a second vertical shaft jo-urnaled at the other end of said table, a sprocket mounted on each one of said shaits, an endless chain engaging said sprockets, a stretching means attached tor said chain and cooperating with said bendingmeans, and a reversible power unit in driving connection with one of said shafts.

5. A combined stretching and bending machine for shaping elongated material into contours, comprising a table, a vertical shaft passing through and being journaled adjacent one end of said table, a forming die xed to said shaft, a second vertical shaft journaled at the other end of said table, a sprocket mounted on each one of said shafts below the table, an endless chain engaging said sprockets, a block attached to said chain and being guided in a slot cut into and along one side of the table above said chain, a fluid pressure motor connected by a vertical pivot to the block, and material gripping means carried in association with the die and with the fluid pressure motor, said fluid pressure motor being adapted to stretch said material as it is wrapped around said forming die.

6. A combined stretching and bending machine for shaping bar stock into contours comprising a turntable, means for rotating the table, a bar stock stretching device, means operatively connecting the stretching device to move itin the same direction as the turntable, a gripping device disposed on the turntable and adapted to holding one end of the bar stock, a second gripping device attached to the stretching device and serving to hold-the other end of said bar stock, and a forming die Vpivotally mounted on said turntable and fixed relation longitudinally of the chain and pivotally secured thereto.

8. A combined stretching and bending machine for bending elongated 'members into predetermined shapes, comprising a turntable, a bending die, means for mounting the die on the turntable, means adapted to anchor the front end of one of said members on the turntable, means for rotating the turntable to wrap said member around the die while the rear end of said member is thereby drawn forward toward the die, fluid pressure actuated means adapted to be connected to the rear end of said member for exerting thereon suicient resistance to said forward movement to stretch said member beyond its elastic limit, and means driven from said turntablerotating means for moving said fluid actuated means forward toward the die at a predetermined rate.

9. A combined stretching and bending machine for bending elongated members into predetermined shapes, comprising a bending die, means adapted to anchor the front end of one of said members adjacent the die, an endless chain for rotating the die to wrapsaid member around it while the rear end of said member is thereby drawn forward toward the die, and uid pressure actuated means mounted on said chain and adapted to be connected to the rear end of said member for exerting thereon suicient resistance to said forward movement to stretch said member beyond its elastic limit.

l0. A combined stretching and bending machine for bending elongated members into predetermined shapes, comprising a bending die, means adapted to anchor the front end of one of said members adjacent the die, means for rotating the die to wrap said member around it while the rear end of said member is thereby drawn forward toward the die, a piston adapted to be connected to the rear end of said member, a hydraulic cylinder housing said piston and mounted in spaced relation to the die, and means for supplying hydraulic pressure to said cylinder in front of the piston whereby to resist forward movement of the piston sufiiciently to stretch said member beyond its elastic limit.

l1. A combined stretching and bending machine for bending elongated members into predetermined shapes, comprising a table, a turntable rotatably mounted thereon, a bending die, means for detachab-ly mountingthe die on vthe turntable, means adapted to anchor the front end of 4one of said members in any desired/position on the turntable, means for rotating the turntable to wrap said member around thedie While the rear end of said member is thereby drawnI forward toward the die, a, piston adapted to be connected to the rear end of said member, a hydraulic cylinder housing said piston, and lmeans pivotally mounting the cylinder on said table on an axis parallel to and a Xed distance from the'axis of the turntable, said cylinder being adapted to receive hydraulic pressure in front of l 9 the piston whereby to resist forward movement of the piston in the cylinder suiiciently to stretch said member beyond its elastic limit.

12. In a stretching and bending machine for shaping bar stock into contours, a turntable, means for connecting one end of said stock to the table, means for rotating the table, a stretching device adapted to be connected to the opposite end of said stock for holding and stretching it,and a forming die mounted on said turntable for bending said stock as the table rotates and being adapted to swing during a bar stock bending and stretching operation about a xed point on the turntable in a direction opposite to the direction in which the turntable rotates.

JAMES s. NIELSEN. CLYDE B. MITCHELLA. 

